CodeSignal - Circle of Numbers

circleOfNumbers.js

/*
Consider integer numbers from 0 to n - 1 written down along the circle in such a way that the distance between any two neighboring numbers is equal (note that 0 and n - 1 are neighboring, too).

Given n and firstNumber, find the number which is written in the radially opposite position to firstNumber.

Example

For n = 10 and firstNumber = 2, the output should be
circleOfNumbers(n, firstNumber) = 7.
*/

function circleOfNumbers(n, firstNumber) {
    let half = n / 2;

    if(firstNumber < half) {
        return firstNumber + half;
    }
    else {
        return firstNumber - half;
    }
}